1. Field of the Invention
This invention relates to an improved apparatus for detecting an overheating condition in a gas cooled dynamoelectric machine, and more particularly to an improved ion chamber apparatus for detecting the presence of submicron particulates associated with overheating of parts in a gas cooled dynamoelectric machine.
2. Description of the Prior Art
Large turbine generators are cooled by forcing a stream of a cooling fluid such a hydrogen over the heat producing parts of the machine. Because of the high flux densities present in the core of such a machine, localized overheating may cause degradation of the insulation disposed on the laminations and the end turns. Because of the potentially catastrophic consequences of such degradation, it is desirable to provide an early warning of an overheating condition.
Apparatus such as those disclosed in U.S. Pat. Nos. 3,428,838; 3,573,460 and 3,427,880 have been developed to provide early warnings of overheated conditions and are generally referred to as generator condition monitors. There have been improvements made on the reliability of the generator condition monitors and the systems in which they are used through such method as those disclosed in copending application Ser. No. 715,258 filed Aug. 17, 1976; copending application Ser. No. 792,836 filed on May 2, 1977 and copending application Ser. No. 796,576 filed on May 13, 1977. All the above referenced copending applications are assigned to the assignee of this application.
Although the apparatus described in the above named patents and applications have considerably reduced the problems associated with early detection of overheating in certain dynamoelectric machines, there is still a need for increasing the sensitivity of the basic generator condition monitor. With an improved sensitivity, an earlier warning of incipient failure within a dynamoelectric machine can be detected, which in turn permits an earlier shutdown of the machine and consequently more assurance of preventing damage to the existing insulation.